Elevator-control system



NOV, 19, 1929. E, BQUTQN 1,736,480

' ELEVATOR CONTROL SYSTEM I Filed NOV. 17. 1927 2 Sheets-Sheet. 1

Fi J.

INVENTOR Edgar MBouron. BY 4 ATTORNEY Nov. 19, 1929; E. M. BouToN 1,736,480

ELEVATOR CONTROL SYSTEM I Filed Nov. 17. 1927 v 2 Sheets-Sheet z Fig.2.

INVENTOR Edgar MBouTon.

BY I A l'TORNEY Patented. Nov. 19, .1929

UNITED. STATES PATENT- orrlcs 8t MANU' FAUIUBING COMIANY,

A conromrron or rnnnsnvmm' ELEVATOR-CONTROL SYSTEM Application filed November 17, 1927; Serial Kc. 288,880,

My invention relates to motor-control systems and it has special reference to control systems for elevators to be operated from a source of alternating-current supply.

'In a motor-control system, especially a control system for elevators and similar apparatus, it is desirable to use the motor as an electrical or dynamic braking device and;

for this reason, it has been proposed to reconnect the elevator motor to the source of supply, with the connections reversed, during the deceleration period, so that the efiect of the suppl circuit upon the motor will be that; of ten ing to reverse the motor, thus causing an electrical braking efiect.

Several different expedients have been suggested and used, but'all of these expedients epend upon switches which are maintained closed in one direction as long as the motor travels in one direction, and require that the motor shall be reversed in order to break the reversing circuits, or an additional speed, responsive device is required to render the reversing device inefiecti've'prior to actual reversal.

' One of the objects of my invention is to I provide means for'causing reverse connec-- tions for the elevator motor to beset up when the motor is travelin in one direction, which connections will ie automatically broken as the motor speed is reduced to a predetermined value.

Another object of my invention is to provide a reversing device, as described in the preceding paragraph, wherein it is unnecessary to reverse the motor in order to break the reversing or dynamic braking connections, and wherein the reversing device needs no additional speed responsive apparatus.

My invention will be described with reference to the accompanying drawin s, wherein Fig. 1 is a diagrammatic view 0 m invention as applied to a single-speed e evatorcontrol system; and

Fig; 2 is a diagrammatic view illustrating my invention as applied to a two-speed elevator-control eqlli ipment.

vReferring to ig. 1, I have illustrated an elevator. car Csuspend'ed from a cable Q1, 4 which passes over a hoisting drum D to a suitable counterweight Cw. Directly coupled to the hoisting drum D, is an induction motor, I

M comprising a multi-phase stator MS and a rotor ME. The stator is illustrated as being of the three-phase type, star-connected.

Upon the shaft S, which couples the motor M and the hoisting drum D, I have shown mounted a rotor R of a reversingor torque motor RM of the single-phase,squirrel-cage. type, the synchronous speedof which is in excess of that of themalri driving motor M. The stator RMS of the motor RM is mounted upon suitable springs 10 and 11 in such manner that rotation of the rotor R will influence the stator RMS to produce rotary motion of the stator in the direction opposite to that in which the rotor is niovecl. The stator RMS has its two terminals; respectively'connected to two of the three-p ase conduotors'of the source of supply, whi conductors are designated as L1, L2 and L3. A third conductor 43 connects to the stator iron.

Upon some portion of the stator RMS, I propose to mount four contact members 12, 13, 14 and 15 for cooperation with contact members 16,17,18 and 19, res ectively. When the main motor M isrotate in either direction, the stator RMS of the reversing motor RM will be moved in the opposite direction to. close contact members 14'-1 8 and 15-'-19 or 12-16 and 13-17, respectively, dependent upon the direction of such rotation.

The direction of movement of the main motor M is controlled: through suitable updirection and down-direction switches 1 and 2 which, in turn, are controlled through the movements of a car switch G8. The operation of either the up-dire'ction or the downdirection switch connects two phase windin ofthe stator of the main motor M selective y aisupply conductors L2 and L3 inforward or reverse order. v

'Upon the outer end of the shaft S is a brake drum BD, against which a brake shoe B8 is normally projected under the force of a spring S'. A suitable brake-releasing coil B, when energized, withdraws the brake shoe Bs from engagement with the brake drum BD to permit the shafts, to rotate freely. The

brake-releasin coil B is suitably controlled by actuation o a brake relay BR.

I have illustrated the brake relay BR as. being provided with two coils, one of which is controlled through the circuit which operates the up-direction and down-direction switches 1 and 2, and the other of which is controlled through contact members 1317 and 15-18 of the reversing motor RM, for a ose hereinafter described.

e operation of my system will best be understood with reference to an assumed clevator operation. Assuming the elevator car to be stationary, the car'switch Cs may be moved to the right to actuate the up-direction switch 1 to cause the car to travel upwardly. The circuit for the up-direction switch 1 extends from line conductor L3, through conductor 20, suitable door and gate switches, indicated by legends, conductor 21, contact members 22, 23 and 24 on the car switch Cs, conductor 25, up limit switch UL, such as is usually provided. at the upper limit of travel to stop the'elevator car, conductor 26, the coilof up-direction switch 1, conductor 27, interlockin contact members a of downdirection switc 2, conductors '28 and 29, the coil on the brake relay BR and conductor 31, to line conductor L2. One phase winding 32 of the stator MS for the main motor M is permanently connected to line conductor L1 and thus the operation of up-dircetion switch l'connects, through its contact members b and 0, the remaining phase windings of the stator MS to line conductors L2 and L3,

- to start the motor M in the up direction.

' mediate'energization of the down-direction- The circuits for these remaining phase windings extend from line conductor L2, through conductor 33, contact members 0 of up-direction switch 1,conductors 34 and 35, and phase winding 36 of the stator MS, to a common or star point 37, at which all of the phase windings 32, 36 and 38 are joined, and from line conductor L3, through conductors 39 and 40, contact members b of up-direction.switch 1, conductor 41, and phase winding 38 on the stator MS,-to the star .point 37. As the motor M starts in the direction of the arrow, the stator RMS of the reversing motor RM will be rotated oppositely, as indicated liy the corresponding arrow, since the stator MS is permanently connected across line conductors L1 and L2, and the inductive effect of. rotation of the rotor R will be to move the stator RMS against the force of the springs 10 and 11 to engage contact members 12- 16 and 13-17.

To stop the elevator car C, the car switch C8 is returned to its central or ofi osition, therebybreaking the circuit to upirection switch 1 at the car switch Cs. Direction switch 1, when deenergized, closes its interlocking contact member's'a, permitting imswitch 2 through contact members 12-16,

which were closed by the reversing motor RM. This circuit extends from line conductor L3 through conductor 48, the iron surrounding the stator RMS, contact members 12 and 16, conductors 44 and 45, the coil of reverse the movement of the rotor MR and, consequently, cause the rotor MR to decelerate rapidly. to bring the car to a stop within a comparatively short distance of travel.

It will be observed that an additional energizing coil 48 is provided upon the brake relay BR, the circuit for which extends from line conductor L3, through conductor 43, contact members 1317 on the reversing motor RM, conductor 49, the coil 48 on brake relay BR and conductor 50, to line conductor L1. This connection ensures that the brake will remain released until the motor MR is substantially stopped.

Since the torque of a single-phase induction motor may be made to vary directly as t-he'speed from zero speed to somewhat less than synchronous speed, it will be seen that by properly designing the springs 10 and 11 to just counterbalance the torque devclfeet of this connection is obviously to tend to oped by the reversing motor RM at some predetermined low speed, the circuit comleted through contacts 12, 13, 14 and 15 may e broken before the final stopping of the main motor M. In this manner, the plug ging of the main motor M is maintained only until thespeed of the main motor M is reduced to a predetermined low value. At this time, the contact members 1216 and 13-17 will be opened under the influence of springs 10 and 11, causing the down-direction switch 2 to dro out and open the circuit to the C011 48 of t e brake releasing relay BR. The brake shoe B8 will now be applied and the elevator car C brought to a complete stop.

Referring to Fig. 2, I have illustrated a twospeed alternating-currentl motor. M having a rotor MR and two stator windand one for low speed, designated as MS" A reversing on torque motor RM, in all respects similar to the reversing motor RM described with reference to Fig. 1, is dispose'd u on the shaft S, which connects the rotor M to the hoisting drum D. A brake is illustrated in this figure as comprisin a brake drumBD', upon which a shoe Bs is normally'maintained in engagement with the ICC ings, one for high speed, designated as MS,

I brake drum BD' through the operation of .carries a car switch Cs which operates to control up and down-direction switches 1 and 2, as described for Fig. 1. The high speed and ,low-speed windings MS and MS" are suitably connected to the up-direction. and down-direction switches 1 and 2 through the operation of a pair of relays 3 and 4, as hereinafter described. A transfer relay TR is provided for selectively actuating the speed relays 3 and 4. In this form of the invention, the reversing motor RM is used to reconnect the slowspee'd-winding MS in the reverse direction whenever the car switch C8 is centered to stop the elevator car. In other words, the slow-speed winding MS" is used as a dynamic 1 brake to reduce the speed of the motor M to a predetermined low value.

The operation of this form of invention is best understood with reference to an assumed operation of the elevator. Assuming, as described for Fig. 1, it is desired to move the elevator car C upwardly, the car switch C8 is moved to the right, thereby I supplyin current to the up-direction switch 1, throng 1 a circuit which extends from line conductor L3 through conductor 60, suitable door and gate switches, appropriately labeled, conductor 61, contact members 62, 63 and 64 on the car switch Cs, conductor 65 and up-l'imit-switch UL, conductors 66 and 67, the coil of up-direction switch 1, conductor 68, interlocking contact members a of down-direction switch 2, conductors 69 and 70, coil 71 on brake-releasing relay BR, and conductor 72, to lineconductor L2.

Up-direction switch 1, when actuated, comletes a' circuit for theslow-spee'd winding S through slow-speed relay 3. The circuit for the energizing coil of relay 3 is completed through contact members d on updirection switch 1 and extends from line conductor L3, through conductors 73 and 74, contact members d of up-direction switch 1, conductors 75 and 76, the coil of slow-speed relay 3, conductor 77, normally closed contact members a on transfer relay TR and con; ductors 78 and 79, to line conductor L2. The slow-speed windings MS now receive current by way of circuits which extend from line conductor L1 through conductors 80 and '81,;contact members b of relay 3, conductor 82 and one phase'83 of the slow-speed winding MS to. a common or star point 84;

from line conductor L2,through conductor 79, contact members 0 of up-direction switch 1, conductor 85, contact members a of relay 3, conductor 86 and the second phase 87 of the stator MS, tostar point 84; and from line conductor L3 through conductors,7 3, 88 and 89, contact members 6 of up-direction switch 1, conductors 90, 91- and 92 and phase 93 of the stator MS to the star point 84. The

motor M thereupon starts-to move the elethe high-speed winding MS through the consequent operations of relays 3 and 4. Upon the actuation of transfer relay TR, its contact members a break the circuit to relay 3,

while its contact members I) complete a circuit for energizing relay 4, which circuit extends from line conductor L3, through conductors 73 and 98, contact members Z) of transfer relay TR, conductor 99, the coil of high-speed relay 4 and conductors 100, 27 and 79, to line conductor-L2. The three phases 101, 102 and 103 of the high-speed winding MS now receive current by way of circuits extending from line conductor L3, through conductors 73, 88 and 89fcontact members I; of up-direction switch 1, conductors and 91', and phase 101, of high-speed winding MS, to a star point 104; from line conductor L1, through conductor 80, contact members 5 of high-speed relay-4', conductor 105, and phase 102 of high-speed winding MS, tostar point 104; and from line conductor L2, through conductor 79, contact members a of up-direction switch 1, conductors 85 and 106, contact members a of highspeed relay 4, conductor 107 and phase 103 of high-speed windin MS to star point 104.

If the car switch 08 is moved to the left to slow down the car, it will disengage its contact member 94, and the transfer relay TR will'drop out, thus opening the circult for the high-speed relay 4 and 'reestablishing of the reversim motor RM contact mem- L1 7 bers 12 and 16, conductors 109 and 110, the coil of down-direction switch 2, conductor 111, contact members a of up-direction switch 1 and conductors 70 and 72, to line conductor L2. Therefore, when the down-direction switch 2 is energized, a circuit is completed for the' slow-speed winding MS", with phases 87 and 93 connected in reverse order.

As was described with reference to Fig. 1, the reverse connection is maintained until the speed of the motor M is reduced toa predetermined value (less than the synchronous speed of the reversing moto'r'RM'), at which time, the reversing motor RM will release its contact members to permit ap lication of the brake and final stopping of t e motor.

The transferrelay TR, therefore,- serves a double purpose, namely, that of determining which of the speed windings MS or MS" will be energized upon initial movement of the car switchCs, and that of insuring reconnection of the slow-speedwinding MS" -nl when the car switch is centered.-

both Fig. 1- and Fig. 2, I have illustrated the additional coil upon the brake relay BR or BR which will be energized through the movements of the reversing motor -.RM.'.

This connection ensures that the brake remains released through the transition periods between the respective energizations oi lip-direction switch 1 and down-direction switch 2 in the stopping operation.

It is thus seen that I ha've'provided a 'system for dynamically braking an alternating- \current' elevator motor, in which the braking effect is maintained'onl .until the speed of the motor has been re uced to-a predeterg mined value, and in which it is unnecessary that the elevator .car should be reversed to break the reversing connections.- This construction obviates the necessity of providing an additional break in the circuit for the plugging or reversingconnections to the motor-controlling relays in the stopping movement.

As the fore oing description is merely illustrative, I do not desire to be limited to the details shown therein, except as defined in the appended claims.

Iclaim asmy invention:

1. In an elevator-control system, a motor, a source of alternating current therefor, means for connecting said motor to said source; to operate said motor, and means for reversing the connections of said motor to said source to produce an electrical braking effect, said means comprisingia magnetic element rotated by said motor, a cooperating magnetic element havin limited movement under the influence of said rotating element, and circuit controllin the connections ofsai motor, said means being operable in response to the movements of said influenced element.

2; In an elevator-control system, an elevator motor, a source of'power, means selectively operable to connect said motor to said means for reversing,

source for movement in either of two directions, an electromagnetic switching device 0 erably responsive to predetermined speeds 0? said motor in either direction for preparing connections for said motor for operation in the reversed direction, and means operably responsive to actuation of said selectively operable means to disconnect said motor for completing said reverse connections, whereby saidmotor will act as a dynamic brake while said motor is operating between said predetermined speeds.-

3'. In a motor-control system, an alternat-v ing-current motor, a source of alternating current, reversing switches selectively operable for connecting said motor to said source for movement. in either of two directions, a switching device electromagnetically responsive to movements of said motor above a predetermined speed in either direction for actuating the reversing switches to operate said motor in the opposite direction, and means operable upon actuation of either of said reversing switches for rendering the other inerable upon disconnection of said motor from said source for reconnecting said motor for reverse operation to produce an electrical braking efi'ect, said means comprising a torque motor havlng a synchronous speed eater than said'main motor, means connectmg the rotor of said torque motor for rotatlon by said main-motor, means for mountmg the stator of said torquemotor for limited movement under the influence of said rotor, and circuit-controlling means operable by movement of said stator.

- '5. In an'elevator-control system, a main motor, asource of alternating current there for, means for connecting sald motor to said source to operate said motor, and means op erable upon disconnection of said motor from said source for reconnecting said motor for reverse operation to produce an electrical braking eifect, said means comprising an electric motor, one elementof which is connected for rotation by said main motor and the other element-of which is mounted for limited movement under the influence of said rotated means operated by movement ofsaid movably mounted element. In testimon'ywhereof, I have hereunto subscribed my name this 7th day. of November,

element,- and circuit-controlling 

